Jet pipe arrangements for jet propulsion engines



J. BRITT April 26, 1960 JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 9 Sheets-Sheet 1 2,933,891 JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 J. BRITT April 26, 1960 9 Sheets-Sheet 2 April 26, 1960 J. BRITT 2,933,891

JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 9 Sheets-Sheet 3 2,933,891 JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 J. BRITT April 26, 1960 9 Sheets-Sheet 4 21 2% ya 16 16b Apri 26, 1960 J. BRITT 2,933,891

JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 9 Sheets-Sheet 5 5 52 5 figd 55 April 26, 1960 J. BRITT 2,933,891

JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 9 Sheets-Sheet 6 April 26, 1960 J BmTT 2,933,891

JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 9 Sheets-Sheet 7 April 26, 1960 JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES Filed June 21, 1954 9 Sheets-Sheet 8 J. BRITT 2,933,891

April 26, 1960 J BmTT 2,933,891

JET PIPE ARRANGEMENTS FOR JET PROPULSION ENGINES I Filed June 21, 1954 9 Sheets-Sheet 9 United Sta "Jack Britt, Totem, Nottingham-England,

the plane of the inlet of the second rET PIPE ARRANGEMENTS son JET PROPULSION menses assignor to Rolls-Royce Limited, Derby, :England, a British comr y 7 Application June 21, 1954, Serial No. 438,091 Claims priority, application-Great Britain Jun e 23,1953

Q Claims. (Cl. 60-3555 This invention relates to jet pipe arrangements for jetpropulsion engines, and relates particularly to jet pipe arrangements in which a downstream portion of the jetpipe is adjustable relative tothe jet propulsion engine for the purpose of alteringthe direction in which the engine exhaust gases pass fromlthe jet pipe to atmosphere to produce a propulsive thrust. Such arrangements find application in vehicles, and particularly in aircrafhincl'uding guided missiles, for manoeuvring purposes. i

An object of this invention is'to provide a light, com- 7 pact and improved construction of jet pipe arrangement for a jet-propulsion engine in which a downstream portion and to'equal extents about an axis normal to said oblique Patented Apr. 26, 1960 planes and passing through the centres of said openings, so that the. longitudinal axis of the downstream portion of the jet-pipe is maintained inthe same plane through out its adjustment. .Preferably the oblique planes of the registering openings of the jet-pipe portions are each at an angle of 45 to the longitudinal axis arms respective portion, or in another preferred arrangement, at 67V2 to said axis. Y 1

According to a feature of this invention, the "jet pipe arrangement may be installed in an aircraft and'th'e upstream jet pipe portion may'b'e rotatively arranged with said first axis parallel to the longitudinal'axis ofthe aircraft," and the extents of rotation of the jet-pipe por 'tions may be such that'the downstream portion is adtjustedbetween a first position, in which its'axis'of discharge is aligned with the axis of rotation of the upstream 'jet-pipe portion, and a second position, in which its axis of discharge is at right angles to said firstv axis. For example in the second position, the downstream portion may have an exhaust outlet directed downwardly to prol duce a propulsive jet parallel to the vertical axis of the aircraft. In order to move the downstream portion from of the jet Pipe is adjustable through arr-angle relative-to the upstream portion, whereby the direction in which "the jet gases pass to atmosphere may be varied. Theinvens tion may be used with advantage when it is desired to adjust the downstream portion of the large angle, such as a right'angle.

According to this invention in one aspect, a jet pipearrangement comprises a fixed .duct portion having at its downstream end a circular outlet,-'a first or upstream movable jet pipe portion having a circular inlet to cooperate with the outlet of the fixed portion, and having a circular outlet, said upstream jet pipe portion being mounted for rotationrelative to the fixed duct portion about a first axis normal. to and passing through the centre of its inlet, and having the plane of its' outlet oblique to the plane of-its inlet, a second or downstream movable jet pipe portion having a circular inlet to cooperf' ate with the outlet of the upstream portion and mounted 'for rotation relative to said upstream portion about a second axis normal to the'plane of the outlet of the upstream jet pipe portion and extending through its centre, the I downstream jet pipe portion having an outlet whereof the axis of discharge is oblique or parallel to its inlet, and means to rotate said upstream jet pipe portion relative to said fixed portion about said first axis to. rotate said downstream portion relative to said upstream portion 7 about said second axis. Preferably theplane of the inlet of the first jet pipe portion is at 45 to the plane of its outlet, and the plane of the inlet of the second jet pipe portion may be at 45 to its axis of discharge. in another preferred arrangement the plane of the inlet of the first jet pipe portion is at 22 /2 to the plane of its outlet, and jet pipe portion is at 67% to its axis of discharge. a

According to this invention in another' aspect, a jet pipe jetpipe through a I the first position tofthe second position whilst maintaining its axis of discharge in a vertical plane, the upstream jet-pipe portion is rotated through a right angleabout said first axis, and the downstream jet-pipe portion is rotated in the opposite sense about the axis normal to the oblique planes through 180 relative to. the upstream portion.

According to a feature of the preferred arrangement in which the oblique planes of the upstream and downarrangement for a jet-propulsion engine'comprises an upstream jet-pipe portion which terminates at its down stream end in a circular opening in a plane oblique to the longitudinal axis of said portion, a downstream jetpipe portion which terminates at its upstream end in a circular opening in a plane oblique to the longitudinal axis of said downstream portion, the circular-openings of said portions being arranged to register, and means to rotate said upstream jet-pipe portion and said downstream jet-pipe portions simultaneously in opposite senses stream jet-pipe portions are each at an angle of 67 /2 to the corresponding longitudinal axis, the jet-propulsion engine is installed in an aircraft and said first axis lies in a plane parallel to a vertical plane through the longitudinal axis of the aircraft and is inclined at 45 b to a line in said plane parallel to the longitudinal axis of the aircraft, or alternatively said first axis lies in the vertical plane through the longitudinal axis of the aircraft and is inclined at 45 with said longitudinal axis, and the downstream portion is arrangedto be angularly' adjusted between a first position in which the axis of discharge is horizontal and a second position in which the axis of discharge is vertical. To. move the downstream portion between the first and second positions, the upstream portion of the jet pipe is rotated about said first axis through two right angles and the downstream portion is rotated about said second axis through four right angles (360) relative to the upstream portionin the opposite sense.

According to another feature of the invention, a jetpipe arrangement, for a jet-propulsion engine comprises a fixed duct portion having at its end a circular outlet, a first or upstream movable jet pipe portion having a circular inlet to co-operate with the outlet of the fixed por tion and having a circular outlet, said upstream jet'pipe 1 vi portion being mounted for rotation relative to thefixed duct portion about a first axis normal to and passing through the centre of its inlet, and having the plane of its outlet oblique to the plane of its inlet, a second'movable jet-pipe portion having a circular inlet to co-operate with the outlet of the upstream portion and having a circentre, and said third jet-pipe portion having an outlet whereof the axis of discharge is oblique to its inlet, and means to rotate said upstream jet-pipe portion relative to said fixed portion about said first axis, said second jetplpe portion relative to said upstream portion abouts'aid second axis, and said third jet-pipe portion relative to said second portionabout said third axis. Preferably the first and third portions are rotated in one sense and the second portion is rotated in the opposite sense whereby the axis of discharge of the third portion of the jet pipe may be maintained in the same plane.

With arrangements in accordance with this feature of the invention, the direction of the jet of exhaust gases leaving the third portion of the jet pipe may conveniently be adjusted through more than two right angles (180).

According to yet another feature of the invention, the means to rotate a pair of adjacent jet pipe portions comprises a toothed ring secured on at least one of the adjacent portions and driven by a meshing pinion. The means to cause relative rotation of the first and second, and second and third portions may comprise a pair of toothed rings, one secured on eachot the adjacent portions to encircle its end which is adjacent the other portion, and a pinion co-operating with said toothed'rings and mounted on a pivotally-mounted gimbal ring, the pivotal axis of the gimbal ring being normal to the axis about which the jet pipe portions rotate, and the axis of rotation of the pinion being normal to the pivotal axis of the gimbal ring. Where the centre of the cooperating inlet and outlet, through which passes the axis about which a pair of adjacent parts rotate relative to one another, is fixed relative to fixed structure (as in the case of the centre ofthe inlet of the second portion, through which passes the second axis abovementioned), the gimbal ring is pivotally mounted in the fixed structure, but where the corresponding centre moves (as in the case of the centre of the inlet of the third portion, through which passes the third axis abovernentioned), the gimbal ring is pivoted to the ends of swinging arms pivoted to fixed structure. The rotation may be effected for example by driving the first movable portion through such a toothed ring, or by driving one of the pinions co-operating with toothed rings on a pair of movable portions, by any convenient form of motor. Where the toothed rings are secured on a pair of movableportions and co-operate with apinion, it is preferred that the toothed rings and the pinion are formed as bevel gears having their apieces at the point of intersection of the pivotal axis of the gimbal ring and the axis of rotation of the jet pipe portions.

Some embodiments of the invention will now be described with respect to the accompanying drawings of which: a

Figure 1 shows in diagrammatic form a side elevation of jet pipe for a jet-propulsion engine in accordance with the invention,

Figure 1A shows a view looking on the end of the jet pipe in the direction of the arrow A in Figure 1,

Figure 1B shows a plan view of the jet pipe of Figure l, the view being in the direction of the arrow B in Figure 1,

Figure 2 shows a view corresponding to Figure 1 of the jet pipe in a second position of adjustment,

Figure 2A is a view looking on the end of the jet pipe of Figure 2 in the direction of the arrow C,

Figure 3 is a view corresponding to Figure l of the jet pipe in a third position of adjustment,

Figure 3A is a view on the end of Figure 3 in the direction of the arrow D,

Figure 4 is a view of another embodiment according to the invention,

Figure 5 is a view corresponding to Figure 4 of the arrangement of Figure 4 in a second position of adjustment,

Figure 6 is a detailed view of part of Figure 4,

4 Figure 7 is a detailed view of another part of Figure 4, Figure 8 shows in diagrammatic form a side elevation of a third embodiment according to the invention,

Figure 9 shows a view corresponding to Figure 8 of the jet pipe in Figure 8 in a second position of adjustment,

Figure 9A is a view looking on the end of the jet pipe of Figure 9 in the directtion of arrow E,

Figure 10 is a view corresponding to Figure 8 of the jet pipe of Figure 8 in a third position of adjustment,

Figure 10A is a view looking on the end of the jet pipe of Figure 10 in the direction of arrow F,

Figure 11 is a side elevation of a practical form of the construction shown in Figures 8 to 10,

Figure 12 is an end elevation of Figure 11,

Figure 13 is an inverted plan of Figure 11,

Figure 14 is a side elevation showing the parts of Figure 11 in a second position of adjustment, and

Figure 15 is a side elevation showing the parts of Figure 11 in a third position of adjustment.

Referring now to Figures 1, 1A and 1B, there is shown diagrammatically a jet pipe 1 for a jet engine 2, which includes a duct portion having at its downstream end a circular'outlet, and exhaust gases pass through the jet pipe from the jet engine to atmosphere. It is usual to provide a restricted nozzle at the downstream end of the jet pipe. The jet pipe is made in two movable cylindrical parts, a first or upstream part 3 and a second or downstream part 4, and these parts join one another in a plane lying at 45 to the axis of the jet pipe as seen in plan view (Figure 1B). The plane containing the outlet of part 3 is thus at 45 to the plane containing its inlet. The upstream part 3 is rotatable about a first axis which is fixed relative to the engine 2, while the part 4'is mounted on the part 3 and is rotatable about a second axis at right angles to the plane in which the parts join one another and passing through the centres of the adjacent ends of the parts.

The plane of the upstream end of the downstream jet pipe part 4 is at 45 to the cylinder axis or axis of discharge of the part 4.

The jet pipe parts 3 and 4 are arranged to be rotated in opposite senses, and as shown in Figure 2, the upstream part 3 is rotated in the clockwise sense as seen from its downstream end and the downstream part 4 is rotated in the anti-clockwise sense as seen from its downstream end. The parts 3 and 4 are rotated through equal angular extents about the second axis from their initial positions, the part 3 also being rotated about the first axis with respect to the engine 2.

In the position shown in Figure 2, the two parts have each been rotated in this manner, the part 3 having been rotated through approximately 24 relative to the engine 2. It will be seen that owing to the plane of the joint between the parts 3 and 4 being at an angle to the transverse plane of the jet pipe, the cylinder axis of the downstream part 4 makes an angle of 45 with the axis of the upstream part 3 as seen in the side elevation, but the axes of the upstream and downstream parts still lie in the same vertical plane (see Figure 2A).

On further rotation of the parts 3 and 4, they reach a position shown in Figure 3 in which the upstream part 3 has been rotated relative to the engine 2 through from its initial position in a clockwise direction seen from the downstream end, and the downstream part 4 has been rotated relative to the upstream part 3 through that is, the parts 3 and 4 have each been rotated through 90 from their initial positions about the second axis but in opposite senses. The downstream part 4 is thus rotated in the anti-clockwise direction seen from its downstream end. It will be seen that the cylinder axis, or discharge axis of the downstream part 4 of the jet pipe now makes an angle of 90 with the cylinder axis of the upstream part 3 of the jet pipe, and that the axes still lie in the same vertical plane.

' gine installed inan aircraft for #in a direction substantially parallel to "the-axis? of the upstream part 3 and a boss 6 on of the 'jet pipe. illustrating the 1 downstream movable portion 9,

of the circular ends of the flangedring 11 (Figures 4, 5, stream end of the main the adjacent" ends of the The-arrangementshown in'Figure li'i'iay' represent the configuration of the jet pipe of a jet-propulsion ennormal forward flight jet pipe, and the arrangement shown in Figure 3 may represent the configuration to provide a vertical thrust for take-off and landing of the aircraft. 5

Clearly the angle between the jet pipe portions in Figure 3 will be double the angle made by the end planes i t of the portions with the axial direction in the configuration shown in Figure 1B, and the latter angle may theoretically be any angle between, but not including,

and 90.

Since Figures 1-3 are purely diagrammatiathe adjacent ends of the upstream and downstream parts 3 and 1 4 of the jet pipe are shown to be elliptical so that the peripheries of the parts 3 and 4 do not mate in the positionsin'termediate the-positions ofFigures 1 and 3. It will be' appreciated however, that the peripheries of the parts 3 and 4 will be made circular in the plane of the joint so that leakage of gases between the joining parts may be reduced to negligible proportions.

aeg-sssgset 16 17 to" prevent their -axial' separatiomth'e inwardly facing" radially-extending surfaces on the'flanges 18a, 18b

co-operating with radially-extending surfaces on the rings 16, 17. In addition a sleeve 19 is provided extendingbetween the rings 16, i7 and arranged co-axially within the ring 13, and the sleeve conveniently has thickened edge portions 19a, 191': formed respectively with inwardly-facing grooves 19c 19d to receive spring sealing rings a,

, 26b which slidingly co-operate with cylindrical surfaces 10 1 on rings 16, 17. v 1

A gimbal ring 21 is provided radially outwardly of ring i8,'and is pivotally supported on fixed structure by means of a pair of trunnion mountings22' carriedby brackets 23 which are secured at their ends remote from the trunnion mountings 22-to the flangedring 11 provided atthedownstream endof the main jet pipepor- -tion 7. Each trunnion mounting 22 comprises a spindle carried by bracket 23 and a cooperating socket formed There are also shown in Figures l3 a boss 5 on the the downstream part 4 These are shown for convenience in degree of rotation of the parts;

Referring now to Figures 4 to 7 there is shown a the invention, the jet pipe having a main fixed portion 7 which receives :jet gases from-the engine (not shown), and which is supported in fixed relation to the engine and surrounding structure. There are also'provided a first or upstream movable portion 8' and a second or the downstream end; of

the portion 9 being formed-as a jet nozzle9a through which the gases are discharged to atmosphere.

The upstream movableportion 8h as a circular inlet 1 and is mounted forrotation relative to' the main portion 7 about a first axis 10, by 'means of an arrangement shown in more detail in Figure 6. The axis 10 joins the centres portion 8 and is at right angles to the plane of the upstream end. A radially- 6) is secured to the downjet pipe portion 7, and a flanged ring 12 is secured to the upstream end of the portion :f 8. The flanged ring 12 has a radially-extending flange 12itwhich extends 7 8, and at the outward extremity of 'the flange 12a are outward from the end of the portion formed two oppositely-extending fianges lzb and. 12:;

which-extend substantially parallel to the wall' of portion fib'A'z-section ring 13'is securedvby one 'of'its end-flanges to the outer sets'c'r'ews 13a, and the part 'of'the flangedring 11 as by other end flange of ring 13- is inwardly directed and abuts the end of flange 1200f ring 12, thus holding the end surface of flangef 12b in contact with therradial face of ring 11.1 The flange 12b is also'formed with acircumfe'r'ential groove 12d on its outer face, and the groove 12d contains a'spring sealing ring14 which co-operates in a gas sealing manner with the web of 'z-section member 13.

in gimbal ring 21. 4

The axis 24 of the trunnion mountings 22 of the gimbal ring 21 on bracket 23 intersects at right angles the axis 15 about which the jet pipe portions 8, 9 rotate rela' tive to one another. The rotational axis 15 andvthe pivotal axis 24 therefore intersect at a point whichis the practical embodiment ofla jet pipe in accordance with centre of the circular joint between the portions-8 and 9. i

- charge25 ofrthe jet nozzle9a may be moved to tliehorizontal position so that the jet gases exhaust horizontally, the sum of the angle 5 between the'first axis 10 about which the upstream portion 8 rotates relative to the fixed structure 7 and the planeof the outletend'of the jet pipe portion' 8 which forms the joint with the jet pipe portion 9, the angle 7 between the plane of the upstream end of the jet-pipe portion 9 which forms the joint with the jet-pipe portion 8 and the axis of discharge '25 of therjet nozzle 10' and the angle at must be 180 (see Figure 5), andrthe angles ,3 plus Conveniently theangles ,Band 7 arevmade equal, and thus each will be 67 /2 The upstream movable portion 8 is arranged to berotated relative to fixed portion 7 about the axis 10 by protric motor2'7.

"The downstream'movable portion 9 is arranged to'be viding gear-teeth lze'on'the externalsurface of flange -12c-, 'and'by providinga pinion 26-which mesheswith the gear teeth 12a and m y for example be driven" by an elecrotated about *axisls in the opposite sense to the rotation' of the" portion 3' but to the same angular extent.

- This is effected by providing a circumferential ring of The outlet of the upstream portion 8 is in a plane oblique to the plane containing the inlet, and co-operates with the inlet of the downstream portion 9. V

The downstream movable portion 9 is mounted for ro-. tation relative to the upstream movable portion 8' about a 'second'axislS which is at rightangles to the plane of portions 8' and 9, which are circularand passes through the-centres of these ends. A

J radially-outwardlyflanged ring 16' (Figure 7) is mounted on the downstream end of portion 8, and an oppositely-facing similar radially-outwardly flanged ring 17 is mounted on the upstream end of portion 9. Surrounding --the'rings'16, l7 is a.channel section-ring 18 whose inweirdly-directed flanges'18a',--18b -engageover the rings teeth lea-on the ring 16 attached to the downstream end of portion 8, and a corresponding ringof teeth 17a on thering 17 attached tothe upstream end of portion 9,

and by providing a pair of pinions 28 which mesh both with the teeth 16a, and with the teeth 17a. The pinions 28- are rotatably mounted on the gimbal ring 21 to be free to rotate about an'axis which is at right angles to the pivotal axis 24 of the gimbal ring 21.

The pinion 28 rotates on a circular-section bush 29 (Fig. 7) which extends through ring 18 and is formed with a flange 29a which lies against the outer surface of ring 18. The-bush 29 is ehollow, and-the ring 18, the

. ring '21 and engages-in the bore of the gimbal ring 21, and-the bush 29' are mutually located with respect to one another on the axis of rotation of pinions 28 by means of a pin 30 which passes through bush 29. However, the ring 18 is free to pivotabout the axis of pinions'28 with'respect to the gimbal ring;21. The pin 30 is'formed with a flange 30a "which lies against the outer 7 minus or must equal 7 Thus fl plus '7' must total surface of the base of the channel-section of the gimbal ring 21 and is secured to ring 21 by setscrews 31 which have threaded engagement with a keep-plate 32. In operation, rotation of the jet pipe portion 8 (including ring 16) relative to the fixed structure and thus to the gimbal ring 21 causes the pinions 28 to rotate about their common axis of rotation and thus to drive the ring 17 and the jet pipe portion 9 in the opposite direction to the rotation of portion 8 but to an equal extent.

The pinions 28 are shown as having straight spur teeth, but it is preferred to make the pinions 28 and the meshing teeth 16a, 17a of bevel form, the apex of the bevel gears lying on the pivotal axis 24.

It will be seen that by rotating the upstream movable portion 8 through 180 relative to main portion 7, about axis 10, and by the consequent rotation of the downstream portion 9 through 180, in the opposite direction about axis 15, the axis 25 of the jet nozzle may be brought from the vetrical position as shown in Figure 4 to the horizontal position as shown in Figure 5, and vice versa. It will be clear that the jet pipe portions 6, 9

' move through 360 relative to one another.

In another arrangement, instead of rotating the jet pipe portions 8, 9 by means of the motor-driven pinion 26 and toothed ring 12, the rotation may be effected by arranging for a pinion 28 to be driven by means of a motor, e.g. an electric motor, mounted on the gimbal ring 21. It will be appreciated that this has the advantage that the drive is taken directly to each of the jet-pipe portions 3, 9 through their respective toothed rings .16, 17.

Vanes may be provided within parts 8, 9, to guide the fiow of gases around the curve, as shown at 33, 34.

It will be clear that numerous possible arrangements may be chosen the values of the angles a, ,3 and 7 being decided in accordance with the requirements of the case.

In another arrangement, it may be arranged that the'jet gases are deflected at say 180 to their original direction by the provision of three movable jet pipe sections, at least two of which each have one end face in a plane oblique to its other end face at the appropriate angle, and the other of which, being the downstream section, has its axis of discharge oblique to the plane of its inlet, the first or upstream section being rotatable relative to a fixed duct portion about a first axis in one sense, for example clockwise, the second movable portion being rotatable about a second axis relative to the first movable portion in the other sense, for example anti-clockwise, and the third or downstream section being arranged to rotate relative to said second portion about a third axis in said one sense.

Referring now to Figures 8, 9, 9A, 10 and 10A, the engine including a fixed duct portion is represented at 52, and the jet pipe is shown as comprising a first or upstream jet pipe section 53, a second or intermediate section 54,

and a third or downstream section 55. The plane of the outlet of the first portion 53 is oblique to the plane of its inlet (being at 45 as shown), the planeof the outlet of the second portion is oblique or (as shown) normal to the plane of its inlet, and the axis of discharge of the third portion is oblique (being at 45 as shown) to the plane of its inlet. Thus the joining planes of the upstream and intermediate sections, and of the intermediate and downstream sections are oblique to the respective longitudinal axes of the sections, and are shown as being at 45, as in the arrangement of Figures 1-3.

The first or upstream section 53 is arranged to rotate about a first axis, which is its own longitudinal axis, relative to'the engine 52, and is indicated as rotating in the clockwise sense seen from the downstream end. The second or intermediate section 5.4 rotatesin the opposite sense about a second axis normal to the plane in which the sections 53, 54 join one another, the end planes of sections 53, 54 rotating in opposite senses by equal 8 amounts relative to fixed structure (such as the engine The section 55 rotates relative to portion 54, in a sense opposite to the sense of rotation of the section 54 relative to portion 53, about a third axis normal to the plane of their adjacent ends, the end planes of sections 54, 55 rotating in opposite senses by equal amounts.

By relative rotation of the portions as described, the jet pipe may be caused to move from the configuration shown in Figure 8, by way of that shown in Figure 9, to the configuration shown in Figure 10. It will be seen that it may be arranged that the longitudinal axes of the jet pipe portions, and particularly the downstream portion from which. the gases exhaust, are maintained throughout in the same vertical plane.

Referring now to Figures 11 to 14, there is shown a practical embodiment of the arrangement illustrated in Figures 8 to 10, and the same references are used in Figures 11 to 14 as in Figures 4 to 7 to indicate the like parts.

The jet pipe has a fixed duct portion 7 and in flow series downstream of it three rotatable jet pipe portions 60, 61, 62, the third of which is formed with a nozzle 63. The pipe portions are of substantially uniform crosssection and in the normal position of the jet pipe the inlet end of the portion and outlet end of the pipe portion 62 are in planes at right angles to the general directions 64a, 64b, 640 of flow of exhaust gas through the jet pipe portions 60, 61, 62, whilst the remaining pipe ends are oblique to this general direction.

The outlet of portion 60 is in a plane oblique, in this example shown as 45, to the plane of its inlet; the outlet of portion 61 is in a plane oblique or (as shown) normal to the plane of its inlet; and the axis of discharge 640 of the third portion 62 is oblique (in this case at 45) to the plane of its inlet. 7

The jet pipe portion 60 is rotatable about a first axis 6411 at right angles to the plane of, and passing through the centre of its inlet end, which is circular, and the jet pipe portion is curved between its ends so as to be of substantially constant circular cross-section normal to its centre-line throughoutits length and the end planes are substantially at right angles to the adjacent portions of the centre-line of the exhaust gas duct. The pipe portion 60 is shown as being rotated by a motor 27 through a mechanism as shown in Figure 6.

The jet pipe portions 60, 61 are relatively rotatable about a second axis at right angles to and passing through the centre of the circular upstream end of portion 61 and downstream end of portion 60 that is about an axis at an angle which is oblique to the general direction 64b of gas flow through the pipe portion 61. The pipe portions 60, 61, are connected drivingly together as shown for the sections 8, 9 in Figure 7. The pipe portion 61 is curved between its ends so as to be of substantially constant circular cross-section normal to its centre-line throughout its length and so that the centre line of the exhaust duct through the pipe portion is normal at each end to the planes of its inlet and outlet.

The jet pipe portions 61, 62 are relatively rotatable about'a third axis which is at right angles to the plane of and passes through the centre of the outlet of the jet pipe portion 61; that is about an axis which is oblique to the general direction 64c of gas flow through the pipe portion 62. The drive for causing rotation of the pipe portions 61, 62 is as shown for the sections 8, 9m Figure 7, except that the trunnions 22 for the gimbal ring 21 of the drive are carried by a swinging yoke member 65 which is pivoted to the brackets 23 about the axis of the other gimbal ring 21 carried by brackets 23 and which in effect provides a pair of rigid arms to prevent relative rotation of the two gimbal rings 21 about the direction of gas flow 64b through the pipe portion 61.

Figures 11, 12 and 13 show the jet pipe parts in a position for obtaining a propulsive jet in the same direction as the gas flow through duct 7.

gimbal ring 21, and the '-'the member 65..is caused to brackets 23.

arsenal On'operation of the motor 27 to rotate portion" 60 relaabout the second axis and by an equal amount relative to'the fixed structure, and in addition'the gimbal ring 21 is caused to swing about its trunnions 22. a

Similarlythe inlet end of'portion 62 will rotate in the opposite direction to the outlet end of portion 61 and by an equal amount relative to, say, the axis of pinions 28 associated with this poinnthe associated gimbal ring 21 is caused to swing about its trunnions 22 and pivot about its mounting'on In Figure 14 portion 60 has been rotated through approximately 24 to cause the axis of discharge 64c of portion 62 to lie at right angles to the first axis 64a, so that if the propulsive jet of Figure 11 were horizontal,

the jet will now be vertically downward. When the arrangement is installed in an aircraft, this'config'uration =may beused to produce'alifting force. j 'In Figure 15 portion 60 has been rotated through 90,

to cause the axis of discharge 64c to become parallel to the first axis 64a, so that the'propulsive jet is exhausted in the opposite direction to that of' Figure 11. In the application to aircraft, this configuration may be used r to provide a braking thrust while"the, configuration of "Figure 11 provides the thrust to "propel the aircraft in its normal direction of flight; i 7

I I claim:

1. A jet pipe arrangement comprising fixedduct s truc; ture having an outlet therefrom,

an upstream jet pipe portion having an inlet end and an outlet end each of circular form, said inlet end registering with said outlet from the fixed duct structure, means supporting said. upstream jet pipe portion on" said fixed duct structurefor rotation about an axis substantially joining the centres of the "fedonsaid fixed duct'structureand carrying s'aid pinion,

" the" pivotal axis of 'thegimbal ring being-normal tothe' axis about'whichfthe jet pipe portions'rotate', and the axis of rotation of the pinion being normal to the pivotal axis of the gimbal ring.

6. A jet pipe arrangement as claimed in claim 5, having 'fixedbracketstextending from said fixed structure and having the gimbal ring associated with the outlet end ofthe upstream jet pipe portion pivotally mounted in the brackets. I a 7'. A jet pipe arrangement as claimed in claim 5, com- =fprising a pair of swinging iarms pivoted at one end to ii s'aidfixedstructure and "having the gimbal ring'wlnch isfassociated with the pair of adjacent jetpipe portions whereof the mutual rotational axis moves relative to said fixed structure, pivoted to theiropposite ends.

w it

- 8: A'jetpipe arrangement as claimed'in claim 5, wherethe toothed rings and the pinion are bevel'gear's h'aving their, apices' at the point of intersection of the pivotal axis of the 'gimbalring and the axis of rotationof'the a 5 jet pipe portions;

9. 'A jet pi e arrangement as claimed in claim 5, comprising gas sealing means extending between the co-oper 1 ating with said toothed rings.

10. A jet ,pipe arrangement as claimed in claim 9,

wherein the gas sealing means comprises cylindricalsurr if faces on each of said toothed rings and a sleeve which extends between thetoothed rings, encircles the cylindrical surfaces and cooperates. in a gas sealing manner therewith. t

,11. A jet pipe arrangement comprising fixed structure 3 having-an outlet therefrom, an upstream jet pipe portion ends, the plane of the outlet end of the upstream jet pipe portion being oblique to said axis, a downstream jet pipe portion connected to receive exhaust gases from the upstream portion, means supporting said downstream jet pipe portion on the upstream jet pipe portion forrotation about an axis at right angles to the plane of the outlet end of the upstream jet pipe portion and extending through the centre of said outlet end, the downstream 'jet pipe portion having a circular inlet end with its .centre on the axis of rotation of the downstream jet pipe portion and with its plane oblique to the general direction of gas flow therethrough, and means to rotate said jet pipe portions from an initial position simultaneously in opposite directions and to equal angular extents about their respective rotational axes.

2. A' jet pipe arrangement as claimed in claimfil, wherein the plane of the inlet end of the first jet pipe portion' -is at right angles to the axis of rotation of this portion.

3. A jet pipe arrangement as claimed in claim 1, wherein the obliquities of the outlet end of the upstream portion and the inlet end of the downstream portion are each v 4. A jet pipe arrangement as claimed in claim 1, wherein the exhaust duct through the jet pipe is of substantially uniform cross-section and the jet pipe portions are of curved form so that the end planes of each portion are substantially at right angles to the centre-line thereof.

5. A jet pipe arrangement as claimed in claim 1, wherein the means to rotate the pair of adjacent jet pipe portions comprises toothed rings, one secured on each of the adjacent portions to encircle its end which is adjacent the other portion, and a pinion meshing with each of said toothed rings, a gimbal ring pivotally mount- V which has "an inlet thereto registering with said'outlet from the fixed structure and which terminates at its downstream end ina circular opening in a plane obliqueto the,

longitudinal axis of said upstream jet pipe portion, a downstream jet pipetportion which terminatesatits upstream end in a circular opening in a plane oblique to thelongitudinal axis of said downstream portion, the

circular openings at the downstream end of the upstream portion and the upstream end of the downstream portion being in register, and means to rotate said upstream jet pipe portion and said downstream jet pipe portion relative to said fixed structure about an axis normal to said oblique'planes from initial positions and.

simultaneously in opposite directions and to equal extents, said means comprising a pair of toothed rings,

means securing said toothed rings respectively on the downstream end of the upstream jet pipe portion and the upstreamrend of the downstream jet pipe portion toencircle the ends, a pinion meshing with said toothed rings, a gimbal ring, means pivotally mounting the gimbal ring 'on s aid fixed structure, and means rotatively mounting said pinion on said gimbal ring, the pivotal axis of the gimbal. ring being normal to the longitudinal axes of the jet pipe portions, and the axis of rotation of the pinion being normal to the pivotal axis of the gimbal'ring.

12. A jet pipe arrangement as claimed in claim 11, wherein the toothed-rings and the pinion are formed as bevel gears having their apices at the point of intersection of the pivotal axis of the gimbal ring and the axis of rotation of the jet pipe portions.

13. A jet pipe arrangement as claimed in claim 11,

comprising gas sealing means extending between and co- 1 tion for rotation relative to said first jet pipe portion about a second axis perpendicular to the plane of the downstream end of the first jet pipe portion, said second jet pipe portion terminating at its-upstream end-in a circular opening in a plane oblique to the general direction of gas flow through the second portion, the said circular openings of said first and second jet pipe portions being in register, said second jet pipe portion terminating at its downstream end in a circular opening with its plane oblique to the general direction of gas flow through the second jet pipe portion; a third jet pipe portion, means supporting said third jet pipe portion on the second jet pipe portion for rotation relative to said second jet pipe portion about a third axis perpendicular to the plane of the downstream end of the second jet pipe portion, said third jet pipe portion terminating at its upstream end in a circular opening in a plane oblique to the general direction of gas flow through said third portion, the circular opening at the downstream end of the second-jet pipe portion registering with the upstream opening of the third jet pipe portion; and means connected to rotate said first and second jet pipe portions and said second and third jet pipe portions respectively from initial positions simultaneously through equal angles about their respective mutual rotational axis, the first and third jet pipe portions being rotated from their initial positions in one sense and the second jet pipe portion being rotated in the opposite sense whereby the rotational axis of the third portion of the jet pipe is maintained in the 'same plane.

15. A jet pipe arrangement as claimed in claim 14,

wherein the exhaust duct through the jet pipe is of substantially uniform cross-section and the jet pipe portions are of curved form so that the'end planes of each portion "are substantially at right angles to the centre-line thereof.

16. A jet pipe arrangement as claimed in claim 14, wherein the means to rotate each pair of adjacent jet pipe portions comprises toothed rings, one secured on each of the adjacent portions to encircle its end which is adjacent the other portion, a pinion co-operating with said toothed rings, a gimbal ring pivotally mounted in said fixed structure and having the pinion rotatively mounted thereon, the pivotal axis of the gimbal ring being normal to the axis about which the pair of jet pipe portions rotate, and the axis of rotation of the pinion being normal to the pivotal axis of the gimbal ring;

17. A jet pipe arrangement as claimed in claim 16, having swinging arms pivoted at one end to fixed structure and having the gimbal ring which is associated with the second and third jet pipe portions whereof the mutual rotational axis moves relative to fixed structure, pivoted to the opposite ends of the swinging arms.

18. A jet pipe arrangement as claimed in claim 16, wherein the means to rotate the jet pipe portions comprises motor means driving the first jet pipe portion.

19. A jet pipe arrangement as claimed in claim 16, wherein the toothed rings and the pinion are formed as bevel gears having their apices at the point of intersection of the pivotal axis of the gimbal ring and the axis of rotation of the jet pipe portions.

20. A jet pipe arrangement as claimed in claim 16 comprising gas sealing means extending between and cooperating with said toothed rings.

References Cited in the file ofthis patent UNITED STATES PATENTS $13,167 Woodhouse Jan. 23, 1894 1,125,642 Blanchard Jan. 19, 1915 1,836,336 Replogle Dec. 1-5, 1931 1,880,098 Mair Sept. 27, 1932 2,537,487 Stone Jan. 9, 1951 2,590,272 Robertson et al. Mar. 25, 1952 FOREIGN PATENTS 703,230 Germany Mar. 4, 1941 1,330 Great Britain Apr. 3, 1879 

